Respiratory management after surgery Flashcards
and 02 therapy
What is pulmonary ventilation?
= breathing
= active process: inspiration occurs due to contraction of muscles that cause negative intrathoracic pressure
- Diaphragm main muscle to displace thoracic cage - Flow is generated due to pressure gradient from atmosphere to alveoli - Expiration is passive after intrathoracic pressure is greater than atmosphere
Lung compliance
= Extent to which lungs expand per unit increase in transpulmonary pressure or stretchiness
- Defined as the volume change per unit pressure change
- Low compliance = lungs are stiffer, and more effort required to inflate alveoli (pulmonary oedema)
- High compliance = easy inflation and loss of elasticity e.g. emphysema
Lung resistance
= obstruction to flow of airways
- Resistance is normally low, most arising from airways e.g. nose of pharynx
- Increases in resistance – oedema, obstruction, spasm, airway obstructive disease
Alveolar capillary network
= has a large surface area that provides the basis for an optimized gas exchange in the lung.
- Each alveolus surrounded by capillary network - Alveoli – thin epithelial cells and capillary – thin endothelial cells lining alveolar
Post operative pulmonary risk factors
- age
- obesity
- health status
- smoking
- lung disease
7 risk factors of surgery
o Low pre-operative Sp02
o Acute resp infection pre-op
o Age
o Pre-op anaemia
o Upper abdominal or intrathoracic
o Surgery duration > 2 h
o Emergency surgery
Post operative pulmonary risk factors evaluation
• History and physical examination
• Chest X-ray
o >50 year age
o Pre-existing pulmonary disease
o Suspected cardiac or pulmonary disease
• Arterial blood gas
o Hypercapnia
• Lung function test - spirometry
• Exercise tolerance test
• Lung scan?
• Type of surgeryPost operative pulmonary complication
- bronchospasm
- cough
- atelectasis
- dyspnoea
- hypoxaemia/hypoxia
- pleural effusion
- pneumonia
Post operative pulmonary complication Bronchospasm
= airway go into spasm and contract
• Intraoperative complication
• Clinical manifestations
o Wheeze, tachypnoea, hypercapnia
• Histamine release causing mast cells degranulation
• Reflex bronchoconstriction due to tracheal stimulation from secretions suctioning
• Treatment: remove cause, beta-2-agonist
Post operative pulmonary complication cough
- Usually initiated in larynx + tracheo-bronchial tree
- Function: maintenance of airway patency
- Airway irritation: irritant receptors in large airways
Most sensitive areas: • Larynx • Carina • Trachea • Major brunch
Postoperative reasons
• Dry airway
• Irritated upper airways
• Cough reflex
Post operative pulmonary complication atelectasis
= incomplete expansion
• Diminished volume affect part or all of the lung
• Common post-operative pulmonary complication
• Pathophysiology
o Post operative pain
o Retain airway secretion
• Diagnosis
o Chest X-ray, lung sounds, ABG, symptoms
• Treatment
o Early mobilisation and incentive spirometry
o Posture drainage, chest wall percussion
o Coughing, nebulised bronchodilators
o Positive pressure ventilation
o Oxygen and antibiotics
Post operative pulmonary complication dyspnoea
- Subjective sensation of uncomfortable breathing
- Common symptom of respiratory disease
- V/Q mismatches
- Lung disease
- May relate to stretch receptor
- Paroxysmal nocturnal dyspnoea
- Posture induced
Post operative pulmonary complication hypoxaemia/ hypoxia
= low blood or tissue oxygen level
causation
- Hyperventilation, V/Q mismatch, decreased alveolar diffusion
Pathophysiology
• Depression of minuet ventilation
• Shunting of gas volume from under ventilated alveoli
• Decrease in gas volume to under perfused alveoli
Clinical manifestiations • dependent on magnitude of hypoxaemia and / or hypoxia • tachypnoea • dyspnoea • cognitive changes • arrhythmias • vasodilation and hypotension cyanosis and coma (very late signs!)
Diagnosis: - Clinical presentation, oxygen saturation, ABG
Treatment
• Reverse cause
• Supplemental oxygen
• Positioning
• Positive pressure ventilation
Post operative pulmonary complication pleural effusion
2 types: transudative (watery and protein-poor) and exudative (protein rich fluid)
Causation:
• imbalance between fluid production and removal
• inadequate lung expansion
• disruption to pleural membrane
Clinical manifestations
• Cough, dyspnoea, pleural friction rub, decreased breath sounds
Diagnosis
• Clinical examination
• Chest x ray
Treatment
• Often nothing as resolves once patient is active
• Chest physiotherapy
• Oxygen therapy if severe
• Can need drainage
Post operative pulmonary complication Pneumonia
- Postoperative pneumonia diagnosed and presents similar to hospital acquired
- Occurs within 5 days postoperative
- Fever, leucocytosis, increased secretions, pulmonary infiltrates on chest x-ray
- Diagnosis: controversial – generally all patient suspected of infection with x-ray infiltrates
- Difficult because many other conditions similar – atelectasis, pulmonary oedema
Treatment
• Oxygen
• Analyses sputum cultures and treat antibiotics empirically
• Position
• Positive airway pressure
PH range
pH < 7.35 or > 7.45
